Pump



P 0, 1969 J. B. WEGMANN ETAL 3,469,532

PUMP

Filed March 25, 1968 United States Patent O M 3,469,532 PUMP Jerome B. Wegmann, Florissant, and John R. Graef, De-

fiance, Mo., assignors to McNeil Corporation, Akron, Ohio, a corporation of Ohio Filed Mar. 25, 1968, Ser. No. 715,643 Int. Cl. F04b 21/04, 19/22; F16 15/16 US. Cl. 103-178 7 Claims ABSTRACT OF THE DISCLOSURE A head assembly for a pump of the so-called lance type in which a highly viscous and sticky material is pumped by reciprocation of a piston in a pump tube. The

piston is carried by a plunger extending upward through- BACKGROUND OF THE INVENTION This invention relates to pumps, and more particularly to head assemblies for pumps particularly adapted for pumping highly viscous and sticky materials, such as certain adhesives.

Heretofore, pumps of the so-called lance type for use in pumping lubricants or the like from a drum have comprised a pump tube or cylinder having a check-valved inlet for the material being pumped at its lower end and a laterally extending outlet below and adjacent its upper end or head. A plunger is reciprocable in the tube, with the upper end of the plunger extending out of the upper end of the tube through a head assembly for attachment to a motor for reciprocating the plunger. At the lower end of the plunger within the tube is a valved piston for drawing the material to be pumped into the tube and forcing it through the tube and out the outlet as the piston reciprocates. Although such pumps have generally served the purpose of pumping lubricant and other materials, they have not been completely suitable for use in pumping high viscosity sticky materials because of leakage at the head assembly of the pump due to sticking of the material to the plunger, and because of deterioration of the head seal due to the high pressure of the material acting on the seal.

SUMMARY OF THE INVENTION Among the several objects of this invention may be noted the provision of a pump of the class above described by means of which high viscosity, sticky materials may be pumped without leakage and seal deterioration at the head assembly of the pump; the provision of such a pump in which the plunger is scraped clean of the material being pumped at its head assembly; the provision of a pump as above described in which the head assembly packing ring is protected against the high pressure of the material being pumped; and the provision of such a pump which is economical to manufacture and reliable in operation.

3,469,532 Patented Sept. 30, 1969 In general, a pump of this invention comprises a tube having a check-valved inlet for material to be pumped at one end constituting its lower end, a head assembly at its upper end and a lateral outlet below and adjacent the head assembly. A plunger having an external diameter smaller than the internal diameter of the tube is reciprocable in the tube and extends out of the upper end of the tube through the head assembly for attachment of the upper end of the plunger to means for driving the plunger. Associated with the plunger within the tube is means for pressurizing the material drawn into the tube through the inlet and for forcing it out of the tube through the outlet on reciprocation of the plunger. The head assembly comprises a tubular body mounted in the upper end of the tube, the body having guide means therein for the plunger and the plunger having a sliding fit in the guide means. A packing ring is provided in the body surrounding the plunger below the guide means for sealing on the plunger. A coil spring surrounds the plunger below the packing ring, this spring, when in its unstressed condition, having an internal diameter smaller than the diameter of the plunger and being expanded on the plunger so as to have a scraping action on the plunger. Means fitted in the body retains the spring in position in the body surrounding the plunger below the packing ring. The spring acts to scrape the plunger and to effect a drop of pressure in the material being pumped as between the pressure of the material in the tube below the spring and the pressure of the material on the packing ring above the spring, so that the packing ring is exposed to reduced pressure. Other objects and features will be in part apparent and in part pointed out hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal section of a pump of this invention; and

FIG. 2 is an enlarged section of the head assembly of the pump of FIG. 1.

Corresponding reference characters indicate corresponding parts throughout the several views of the drawlngs.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, a pump of this invention is shown to comprise a pump tube or cylinder 1. Threaded on the upper end of the pump tube 1 is an outlet body 3 having a laterally extending outlet fitting 5 threaded into the body 3 at one side. The fitting 5 holds in place an outlet check valve 7. A plunger 9 extends through the body 3 into the pump tube 1, and a head assembly, indicated generally at 11, is threaded in the outlet body 3 for closing the upper end of the pump tube, as will appear.

Threaded in the lower end of the pump tube 1 is an inlet body 13 having a check valve 15 therein. The plunger 9 has an external diameter smaller than the internal diameter of the tube 1 and is comprised of an upper operating rod 17 extending upwardly through the head assembly 11, a piston rod 19 and a tubular connecting rod 21 connected at its upper end to the operating rod 17 and at its lower end to the piston rod 19. The piston rod 19 has a reduced-diameter lower portion, a piston 23 being slidable on the latter. The piston 23 is of inverted cup-shape and is provided at its lower end with a valve seat 25 engageable by a valve 27 threaded on the lower end of the piston rod 19. The piston 23 is biased downwardly to a valve-closed position by a spring 29 surrounding the upper portion of the piston rod and reacting from the lower end of the tubular connecting rod 21 against the upper end of the piston 23. A plurality of outlet ports 31 are spaced around the periphery of the piston 23 at its upper end for communication with the annular space in the tube 1 around the plunger 9. The upper end of the rod 17 is threaded as indicated at 32 for connection to an air motor or other suitable means for reciprocating the plunger and piston in the tube.

The operation of the pump mechanism described thus far is as follows: The pump is inserted through a bung in a drum of material to be pumped and the threaded upper end 32 of rod 17 is connected to a suitable reciprocating motor. Upon an upstroke of the plunger 9, the operating rod 17, connecting rod 21, piston rod 19 and piston 23 move upwardly in the tube 1 thereby opening the check valve 15 and drawing material from the drum into the tube 1 beneath the piston 23. Upon a succeeding downstroke of the plunger 9 and piston 23, the check valve 15 closes and valve 27 disengages from the seat 25 on the piston. Thus, as the plunger moves downwardly in the tube 1, the piston 23 is held upwardly against the bias of spring 29 by the pressurized material and the material passes into the piston, through the ports 31 into the annular space between the plunger and the tube, and out the check valve 7 in outlet fitting 5. Successive downstrokes and upstrokes of the plunger in the tube forces additional charges of the material out the outlet fitting for delivery to its intended place of use via a suitable conduit connected to the fitting.

As noted above, when a high viscosity material, such as an adhesive, is dispensed by pumps of this type, the material clings to the surface of the plunger rod 17 and has a tendency to chew up the seal for rod 17 in head assembly 11, resulting in leakage. In addition, the packing ring in the head assembly is subjected to the high pressure of the material and therefore deteriorates rapidly.

In accordance with the present invention, the head assembly 11 includes means for scraping the plunger rod 17 free of the high viscosity material being pumped and for effecting a reduction in pressure of the material on the packing ring. As shown in FIG. 2, the head assembly comprises a tubular body 33 threaded as indicated at 35 for reception in the upper end of the outlet body 3. An O-ring 37 seals the body 33 in the outlet body. The body 33 has abore 39 and first and second counterbores 41 and 43 therein. A tubular bushing 45 is seated in the upper end of the first counterbore 41 around the plungen-The bushing has an internal diameter forming a sliding fit with the plunger rod 17 for guiding the plunger as it reciprocates. A packing ring 47 is provided in the body around the rod 17 below the bushing 45 for sealing in the bore 41 and on the rod 17, with the upper face of the packing ring 47 engaging the lower face of the bushing 45. The packing ring is preferably of inverted U- section. A steel spring retainer 49 is seated in the upper end of the second counterbore 43 and is retained therein by a washer 51 and a split ring 53 expanded into an internal annular groove 54 in the body 33. This retainer holds a coil spring 55 in position surrounding the rod 17 below the packing ring 47. This spring is formed so that, in its unstressed condition, it has an internal diameter smaller than the diameter of the rod 17, and is expanded in being applied to the rod so as to act as a scraper to scrape off the rod any viscous sticky material which may cling to the rod as the rod moves upward. Thus the rod is scraped clean to prevent viscous sticky material which might otherwise cling to the rod from chewing up the packing ring 47. The spring is preferably made from spring wire of rectangular cross-section. In a typical installation in which the rod 17 has a diameter of about one inch, the spring is wound so that its inside diameter is about .030 inch smaller than the diameter of the rod, and is then internally ground so that its final inside diameter (in its unstressed condition) is about .005 inch smaller than the diameter of the rod. Thus, as expanded on the rod, the spring in effect provides a .005 inch compression. The spring retainer 49 comprises a ring having an inwardly directed annular flange 49a at its upper end. The spring 55 is retained between this flange and a cupped or wave washer 57 seated against the washer 51. The wave washer 57 serves to accommodate for tolerance variations so that the spring 55 is held against up and down movement in the retainer 49. The spring 55, in addition to functioning as a scraper for the rod 17 as above described, also functions to effect a drop of pressure in the material being pumped as between the pressure of the material in the tube below the spring and the pressure of the material on the packing ring 47 above the spring so that the packing ring is exposed to reduced pressure. This drop in pressure occurs because of the restriction in the passage for the material caused by the spring between the space below the spring in the tube and the space above the spring at the lower face of the packing ring. With the packing ring exposed to reduced pressure instead of the high pump pressure, its effective life is prolonged.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A pump comprising a tube having a check-valved inlet for material to be pumped at one end constituting its lower end, a head assembly at its upper end, a lateral outlet below the head assembly, a plunger having an external diameter smaller than the internal diameter of the tube reciprocable in the tube and extending out of the upper end of the tube through the head assembly for attachment of the upper end of the plunger to means for driving the plunger, and means associated with the plunger within. the tube for pressurizing the material drawn into the tube through the inlet and forcing it out of the tube through the outlet on reciprocation of the plunger, said head assembly comprising a tubular body mounted in the upper end of the tube, said body having guide means therein for the plunger, said plunger having a sliding fit in said guide means, a packing ring in said body surrounding the plunger below said guide means and sealing on the plunger, a coil spring surrounding the plunger below the packing ring, said spring, in its unstressed condition, having an internal diameter smaller than the diameter of the plunger and being expanded on the plunger so as to have a scraping action on the plunger, and means in said body for retaining the spring in position in the body surrounding the plunger below the packing ring, said spring acting to scrape the plunger and to effect a drop of pressure in the material being pumped as between the pressure of the material in the tube below the spring and the pressure of the material on the packing ring above the spring, so that the packing ring is exposed to reduced pressure.

2. A pump as set forth in claim 1 wherein said spring is formed of rectangular cross-section wire.

3. A pump as set forth in claim 1 wherein said spring retaining means comprises upper and lower annular elements secured in said body below the packing ring; the spring being held between said elements.

4. A pump as set forth in claim 1 wherein said spring retaining means comprises a tubular element secured in said body below the packing ring and annular elements projecting inwardly at the upper and lower ends of said tubular element, the spring being held between said annular elements, and having a close fit in said tubular element.

5. A pump as set forth in claim 4 wherein a cupped washer is interposed between the lower end of the spring and the lower annular element.

6. A pump as set forth in claim 1 wherein said tubular body as a counterbore toward its lower end below the packing ring, said spring retaining means comprising a tubular element fitted in the upper end of said counterbore, and element having an inwardly directed annular flange at its upper end, and an annular washer at the lower end of said tubular element projecting inward therefrom, said spring being held between said flange and said washer and having a close fit in said tubular element.

7. A pump as set forth in claim 6 wherein a cupped washer is interposed between the lower end of the spring and the said annular washer.

6 References Cited UNITED STATES PATENTS 1,128,089 2/1915 Astrom 103-178 2,390,832 12/1945 Ginter 1O3178 5 2,833,577 5/ 1958 Reynolds 277-24 2,966,376 12/ 1960 Reynolds 27724 FOREIGN PATENTS 478,455 1/ 1938 Great Britain. 10 408,778 4/ 1934 Great Britain.

HENRY F. RADUAZO, Primary Examiner US. Cl. X.-R. 15 103153; 277-24 

